To establish specificities of naturally occurring antibodies in sera from healthy humans, and healty gibbon apes against envelope antigens of type C viruses from primates. Examination of enhancing and inhibiting factors of virus-induced primary tumors from blood platelets. Alteration of specificity of type C virus-associated surface antigens after transplantation or culture passage of mouse malignant cells. Bridging between classical and molecular immunologies. Model experiments of immunotherapy of AKR spontaneous leukemias using a preparation of Streptococcus pyogenes. BIBLIOGRAPHIC REFERENCES: Aoki, T., Liu, M., Walling, M.J., Bushar, G.S., Brandchaft, P.B. and Kawakami, T.G.: Specificity of naturally occurring antibody in normal gibbon serum. Science 191: 1180-1183, 1976. Aoki, T., Kvedar, J.P., Hollis, V.W. Jr. and Bushar, G.S.: Streptococcus pyogenes preparation OK-432: Immunoprophylactic and immunotherapeutic effects on the incidence of spontaneous leukemia in AKR mice. J. Natl. Cancer Inst. 56: 687-690, 1976.